Water-dilutable binder mixture, and its use for the production of a two-layer metallic paint coating

Abstract

A water-dilutable binder composition for the preparation of a metallic base paint comprising (A) a water-soluble condensation product derived from (a) a saturated or unsaturated oil-free polyester containing OH-groups having been prepared from at least one polycarboxylic acid and at least one polyhydric alcohol, (b) a polycarboxylic acid mixture containing trimellitic acid, (c) at least one epoxidized oil, and (d) a basic compound; (B) an additive selected from the group consisting of one or more metal powders, one or more metal powders in combination with at least one other pigment, and one or more metal powders in combination with at least one other dyestuff; and (C) at least one water-miscible solvent a process for the preparation of a two-layer metallic paint coating with said composition.

We claim: 
     
       1. A water-dilutable binder composition for the preparation of a metallic base paint comprising (A) a water-soluble condensation product derived from (a) a saturated or unsaturated oil-free polyester containing OH-groups having been prepared from at least one polycarboxylic acid and at least one polyhydric alcohol,   (b) a polycarboxylic acid mixture containing trimellitic acid,   (c) at least one epoxidized fatty oil, and   (d) a basic compound;   (B) an additive selected from the group consisting of one or more metal powders, one or more metal powders in combination with at least one other pigment, and one or more metal powders in combination with at least one other dyestuff; and   (C) at least one water-miscible (compatible) solvent.   
     
     
       2. A binder composition according to claim 1, wherein component (a) has a hydroxy number between 80 and 120 and component (c) has an epoxy equivalent between 100 and 360. 
     
     
       3. A binder composition according to claim 1, wherein component (B) is predominantly aluminium powder. 
     
     
       4. A binder composition according to claim 1, wherein component (B) is present in an amount of from 0.8 and 50% by weight, referred to the binder. 
     
     
       5. A binder according to claim 1, wherein the weight ratio of solids of component (a) to component (b) is between 50:50 and 90:10. 
     
     
       6. A water-dilutable binder composition as claimed in claim 1 for the preparation of a metallic base paint comprising (A) a water-soluble condensation product derived from (a) a saturated or unsaturated oil-free polyester containing OH-groups having been prepared from at least one polycarboxylic acid and at least one polyhydric alcohol,   (b) a polycarboxylic acid mixture containing trimellitic acid,   (c) at least one epoxidized fatty oil, and   (d) a basic compound;     (B) an additive selected from the group consisting of one or more metal powders, one or more metal powders in combination with at least one other pigment, and one or more metal powders in combination with at least one other dyestuff; and   (C) at least one water-miscible (compatible) solvent;   wherein component (a) has a hydroxy number between 60 and 150, component (B) is predominently aluminium powder and which component is present in an amount between 0.8 and 50% by weight referred to the binder, and wherein the weight ratio of solids of component (a) to component (b) is between 50:50 and 90:10.   
     
     
       7. A binder according to claim 1 or claim 6, wherein component (A) is a condensation product derived from (a) a polyester based on phthalic anhydride, trimethylolpropane and 2,2-dimethylpropanediol, (b) a bis-anhydride from 2 mols of trimellitic acid anhydride and one mol of propanediol, (c) an epoxidized soya-bean oil having an epoxy equivalent weight between 170 and 180, and (d) dimethylaminoethanol; component (B) is aluminium powder; component (C) is ethanol; and the binder additionally contains finely-divided silica. 
     
     
       8. A process for the preparation of a two-layer metallic paint coating consisting of a first metallic base paint layer and a second covering lacquer layer on a substrate, which comprises applying a binder composition according to claim 1 diluted with water to the substrate to form the metallic base paint layer, drying the base layer to obtain a tack-free surface, and then applying a covering lacquer layer to the dried base layer. 
     
     
       9. A process according to claim 8 wherein the base layer is dried within a period of time of less than 10 minutes at ambient temperature. 
     
     
       10. A process according to claim 8 or claim 9, wherein the binder composition according to claim 1 diluted with water has a water content of from 40 to 70% by weight based upon the total amount of solvent and water contained therein.